Hot-air swept mills, with series arranged, hammer-crushing chamber, and peg and disk pulverizing chamber



Jan. 18, 1955 w, c, ER 2,699,898

HOT-AIR SWEPT MILLS, WITH SERIES ARRANGED, HAMMER-CRUSHING CHAMBER AND PEG AND DISK PULVERIZING CHAMBER Filed April 6, 1951 3 Sheets-Sheet l INVENTOR WAYNE 6. Ross/as ATTORNEY W. C. ROG ERS Jan. 18, 1955 HOT-AIR SWEPT MILLS, WITH SERIES ARRANGED, HAMMER-CRUSHING CHAMBER AND PEG AND DISK PULVERIZING CHAMBER Filed April 6, 1951 v 3 Sheets-Sheet 2 INVENTQR War/v5 G. Ros-Ems ATTORNEY Jan. 18, 1955 w. 0. ROGERS 2,699,898

HOT-AIR SWEPT MILLS, WITH SERIES ARRANGED, HAMMER-CRUSHING CHAMBER AND PEG AND DISK PULVERIZING CHAMBER Filed April 6, 1951 3 Sheets-Sheet 5 INVENTOR WHYNE C. fioazms ATTORNEY United States Patent HOT-AIR SWEPT MILLS, WITH spurns AR- RANGED, HAMMER-CRUSHING BER, AND PEG AND DISK PULVERIZING CHAMBER Wayne C. Rogers, Worcester, Mass., assignor to Riley Stoker Corporation, Worcester, Mass., a corporation of Massachusetts Application April 6, 1951, Serial No. 219,611

Claims. (Cl. 241543) This invention relates to pulverizing apparatus, and more particularly to the construction and arrangement of an apparatus having revoluble hammers to crush material, and revoluble impact elements or pegs to reduce the crushed material to a fine powder.

Machines of this type have been widely utilized for preparing pulverized coal for combustion in a furnace, and in general their operation has been highly satisfactory. It is found however that when the coal delivered to the machine contains considerable surface moisture, the capacity of the machine is very appreciably reduced. In some cases the presence of'trainp iron or other hard foreign bodies mixed with the incoming coal has caused breakage or excessive wear. The hammers in some machines wear unevenly and require frequent replacement Since these hammers are not readily accessible, considerable time and labor may be involved.

It is accordingly one object of the invention to provide a pulverizing apparatus which will have a very large capacity in relation to the physical size of the machine.

It is a further object of the invention to provide a pulverizing apparatus which will be capable of handling very wet incoming material without excessive reduction'in its capacity.

It is a further object of the invention to provide a pulverizing apparatus of the hammer-peg type so constructed that such wear as occurs'on the hammers will be more uniformly distributed.

It is a further object of the invention to provide a pulverizing apparatus of the hammer-peg type so constructed as to facilitate replacement of'wornpa rts.

It is a further object 'of the invention to provide a hammer-peg pulverizer which WiIY'rernain free from damage or undue wear even'though hard foreign bodies may enter the machine with the coarse material.

It is a further object of the invention to provide a. hammer-peg pulverizer which will be exceedingly efficient in operation h m ara elv small amoun o power will be required to drive the machine.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of'parts set forth in the specification and covered by the claims appended hereto.

In accordance with the invention in its preferred form there is provided a hollow casing which is divided internally into a crushing chamber and a pulverizing chamber, the latter having a centrally located outlet on the side opposite the crushing chamber. This outlet preferably leads directly into a fan chamber having a tangentially directed outlet. A erushing rotor, a pulverizing rotor, and a fan rotor are located within the said chambers respectively, and these rotors are preferably mounted on a single horizontal rotatable shaft The crushing rotor preferably comprises one or more vertical disks having crushing hammers mounted on their peripheral portions, and the pulverizing rotor comprises a considerably larger vertical disk having pulverizing pegs projecting from its;

outlet side. Stationary pegs are preferably mounted on the casing wall, adjacent to the rotor pegs. An inlet chute leads the coarse material, preferably accompanied by a stream of hot air, into; the upper portion of the crushing chamber, above the crushing rotor. Directly beneath the crushing rotor there is provided a perforated grid which extends throughout a considerable are, preferably about 180 degrees, substantially concentric with the shaft. A

l atented Jan. 18, 195,5

breaker plate forms a portion of the peripheral wall of the crushing chamber, above the grid and in front of the inlet. In the rear portion of the peripheral wall of the crushing chamber there is provided an opening leading to a tramp metal pocket. An upright wall is located between the crushing rotorand the pulverizing rotor, and all the .air and crushed material is compelled to travel downwardly through the grid. The openings in the grid are preferably formed as slots which are considerably inclined forwardly and outwardly with respect to-the corresponding radii. Thus these slots are tangential to an imaginary cylinder coaxial with the shaft, and they guide the escaping air and crushed material in such directions as to maintain the whirl which has been impartedpthereto by the crushing hammers. An inclined surface is located beneath the grid and is shaped to deflect the material laterally into 'the pulverizing chamber and around the outside of the pulverizing rotor disk without appreciably interfering with the whirling motion .of the material. The opening through which the material enters 'the pulverizing chamber is preferably shaped as a circular ring sector extending through approximately degrees ibeneath the shaft and coaxial therewith.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. l is a vertical longitudinal section through a pulverizing apparatus, the section being taken on the "line 1.- 1 of Fig. 2;

Fig. 2 is a section, on a reduced scale, taken on the line 22 of Fig. 1;

Fig. 3 is a sectional view, at a greatly enlarged scale, of a small portion of a grid as shown in Fig. 2;

Fig. 4 is a plan view of one of the pieces. which form the grid;

Fig. 5 is an elevation of the piece shown in Fig. 4;

Fig. 6 is a section taken on the line 66 of Fig. 5;

Fig. 7 is a section taken on the line 7-7 of Fig. l; and

Fig. 8 is a fragmentary sectional view, similar to a portion of Fig. 1, showing a slight modification.

The embodiment illustrated comprises a hollow casing 10 which is divided internally into a centrally located pnl verizing chamber 11, a crushing chamber 12 at one side of the pulverizing chamber, and a fan chamber 14 atthe other side of the pulverizing chamber. An upright partition wall 15 is provided between the pulverizing chamber 11 and the fan chamber 14, and this wall has a circular opening 16 therethrough which forms a centrally located outlet for the pulverizing chamber. The fan chamber 14 has a tangentially directed outlet 17 (Fig. 2). A horizontal shaft 19 extends through the casing 1i) and is rotatably supported in two bearings 202'i) loeated on opposite sides of the casing.

Within the pulverizing chamber 11 the shaft 19 carries a pulverizing rotor comprising a central hub 21 and a vertical disk 22. Annular rows of pulverizing pegs 24 project from the outlet side of the disk toward the wall l5,'and a few pegs 25 may be provided on the other side of the disk. Annular rows of stationary pegs 26 are mounted on the wall 15 in position to intermesh with the revolving pegs 24. The stationary pegs 26 are preferably much longer than the pegs 24. For a. more detailed description of the various pegs and the means for supporting the same, reference may be had to theprior patent to Andrews No. 1,840,380, granted January 12, 1932-. Suitable radially extending reiector blades 27 are mounted; on the hub 21 to revolve adjacent the outlet opening in and prevent the escape of coarse particles of material. A fan rotor 29 having blades 30 thereon is mounted on the shaft 19 within the fan chamber 14.

Within the crushing chamber 12, the shaft 19 carries a crushing rotor comprising a central hub 32 and two axially spaced vertical disks 33 secured to the hub. Crush-. ing hammers 34 are mounted on the peripheral portions of the disks 33, these hammers being pivotally secured to the disks by means of pins 35. The hammers are shaped to provide wide flat front surfaces for engagement with the incoming coarse material.

The crushing chamber 12 is separated from the pulverizing chamber 11 by an upright partition wall 37 spaced appreciably from the disk 22 and having an opening 38 therein through which the shaft 19 extends. This wall comprises a lower plate 39 of semi-circular shape, and an upper plate 40 of semi-circular shape. These plates are connected by two splice members 42 (Fig. 7) located on opposite sides of the shaft, the splice members being welded to the lower plate and releasably fastened to the upper plate by screws 43. The radius of the lower plate 39 slightly exceeds the radius of the circle through which the outer surfaces of the hammers 34 travel. The radius of the upper plate 40 is considerably greater than that of the lower plate 39, but somewhat less than that of the pulverizing chamber 11. An opening 44 is provided beneath the wall 37 to form an inlet for the pulverizing chamber, this inlet being shaped as a circular ring sector extending through approximately 180 degrees coaxial with the shaft 19, as shown in Fig. 7.

Means is provided to retain the material within the crushing chamber 12 until it has been properly crushed by the hammers 34, and to prevent any large hard foreign bodies from reaching the pulverizing chamber. For this purpose an arcuate grid 46 is mounted beneath the hammers and extends between the partition wall 37 and the opposite wall of the crushing chamber, this grid being semi-circular in form and spaced slightly outward from the hammers. The grid is supported by means of members 47 fastened to the edge of the lower plate 39 and by means of members 48 fastened to the opposite wall. The grid 46 is shaped to provide a multiplicity of openings in the form of transverse slots 50 which are inclined forwardly and outwardly at a considerable angle with respect to the corresponding radii. In the embodiment illustrated, this angle is approximately 45 degrees. For convenience in manufacture and assembly, the grid is made up of a series of separate elongated bars 51, one of which is shown in Figs. 4, and 6. It will be noted that the joints between adjacent bars lie in inclined planes extending through the centers of alternate slots 50.

Referring now to Fig. 2, it will be seen that an upright feed chute 55 is mounted on the top of the crushing chamber 12 in position to deliver coarse material to an inlet passage 56 directly above the revolving hammers 34. The material is supplied to the feed chute 55 at a desired rate from a hopper 57 by means of a revoluble pocketed drum 58. Hot air is supplied to the feed chute through a duct 60 provided with a damper 61. If desired, relatively cool air may be admitted to the duct 60 directly from the atmosphere through an inlet passage 62 provided with a damper 63. As the coarse material falls through the inlet passage 56 into the path of the hammers 34, it will be struck'by the hammers and thrown against a breaker plate 65 which forms a portion of the peripheral wall of the crushing chamber 12, in front of the inlet passage and above the grid 46. Between the lower edge of the breaker plate and the grid there is mounted a nose piece 67 which extends inwardly close to the path of the hammers. Immediately above the grid and adjacent the up-running portion of the crushing rotor there is provided a tramp metal escape passage 69 which leads outwardly to a tramp metal pocket 70. A removable plate 71 permits access to this pocket from the outside of the machine.

The revolving hammers 34 will produce a whirling mixture of crushed material and air, which will escape through the grid 46, and because of the inclined arrangement of the grid slots 50, the escaping mixture will travel in tangential directions tending to maintain the whirl. In the interests of efliciency, the saving of power in the operation of the machine, and the maintenance of full capacity, it is desirable that the whirl be continued as the stream of material enters the pulverizing chamber 11. However, the grid 46 extends for approximately 180 degrees only, and because of the tramp metal pocket 70 and the inlet passage 56 the material which passes through the grid cannot follow a curved or whirling path for 360 degreees until it has entered the pulverizing chamber. In order to avoid this difliculty, means is provided to deflect the material laterally toward the inlet opening 44 of the pulverizing chamber. For this purpose a plate structure 73 is mounted beneath the grid, this structure having an upper surface which flares radially outward in a direction toward the opening 44. Preferably this upper surface is a surface of revolution coaxial with the shaft 19, and as shown in Fig. 1 it is a frusto-conical surface throughout the entire width of the plate structure. In Fig. 8 a slightly dificrent plate structure 75 is provided,

the upper surface thereof being frusto-conical adjacent to the opening 44, and the portion of the upper surface remote from the said opening being concave to form a fillet 76 of relatively long radius. For ease in manufacture and assembly, the plate structure 73 is preferably made of several separate pieces of identical shape, as indicated in Fig. 7.

Since small pieces of hard foreign material may travel through the grid slots and enter the pulverizing chamber 11, a pocket 78 (Fig. 7) is preferably provided in the lower portion of this chamber to receive such pieces. A removable plate 79 affords access to the pocket 78.

As shown in Fig. 2, a removable door 81 is provided in the peripheral Wall of the casing adjacent the breaker plate 65. By removing this door, access may be had to the interior of the crushing chamber 12 as required for replacement of the breaker plate 65, the nose piece 67, the hammers 34, and the grid 46, without disturbing the feed chute 55.

It is also desirable to afford access to the pulverizing chamber 11 and the fan chamber 14 without disturbing the feed chute 55. For this purpose the upper portion of the casing 10 which encloses the chambers 11 and 14 is made separate from the lower portion thereof, as well as separate from the vertical plate 40 forming the adjacent wall of the crushing chamber. A semi-circular rib 83 (Figs. 1 and 7) is provided on this upper casing portion in position to overlie a similar semi-circular rib 84 on the adjacent side of the plate 40, these ribs being coaxial with the shaft 19. A gasket 85 of rubber or other resilient material is provided between these ribs to form a tight seal.

The operation of the invention will now be apparent from the above disclosure. The shaft 19 will be rotated by a suitable motor or other source of power, and the fan blades 30 will cause a powerful current of air to flow through the entire machine. This current will inelude hot air from the duct and cool air from the passage 62, in the proportions determined by the adjustments of the dampers 61 and 63. The air current will flow through the passage 56 into the crushing chamber 12, thence through the grid 46 and the opening 44 into the pulverizing chamber 11, around the outside of the disk 22, through the central opening 16 into the fan chamber 14, and thence through the fan chamber outlet 17. The coarse and frequently wet material in the hopper 56 will be fed downwardly at a desired rate by the drum 58, and will drop into the path of the revolving hammers 34. The hammers will strike the material and throw it against the breaker plate 65, so that the material will be broken up into small pieces. Much of the crushed material leaving the breaker plate will be thrown against the nose piece 67, which will to a considerable extent shield the grid 46 from wear. The reduction in the size of the material will enormously increase the surface area of the particles, and this will cause the moisture to evaporate from these particles very rapidly into the stream of hot air, particularly under the extremely turbulent mixing conditions brought about by the rapidly revolving hammers. With the air temperature properly controlled for the existing moisture content of the incoming coarse material, the material will be very thoroughly dried while within the crushing chamber. Any hard foreign particles which are too large to pass through the grid will be ejected through the passage 69 into the pocket 70.

The stream of air and crushed material will flow outwardly through the grid slots 50, and because of the outward and forward inclination of these slots the stream will still be whirling as it leaves the grid. Furthermore, there will be comparatively little erosive action on the grid. As the material leaves the grid slots it will immediately impinge on the plate structure 73, which will deflect the material laterally through the opening 44 into the pulverizing chamber 11 without interfering with the tangential or whirling motion of the material. The pegs 25 will aid in maintaining this whirling motion. The air current will carry the material around the outside of the rotating disk 22 and inwardly toward the central opening 16. Particles which are already sufiiciently fine will escape through this opening with the air stream, whereas coarse particles will be held outwardly by centrifugal action until they have been further pulverized by the revolving pegs 24 in cooperation with the stationary pegs 26. The revolving rejectors 27 will help to prevent the escape of coarse particles through the opening 16. The fine particles Which do travel through this opening with the air current will pass through the fan chamber 14 and thence through the tangential outlet 17 thereof to a place of use or deposit. Since the material reaching the pulverizing chamber 11 is thoroughly dry, the machine can be operated at comparatively high capacities without difficulty.

Other advantages of the invention will be noted. The two rows of hammers 34 provide striking surfaces of considerable width, which contributes to the high crushing capacity of the machine. The wear on these surfaces will be comparatively uniform, since the coarse material enters the crushing chamber 12 in a generally radial direction and is distributed substantially evenly across the width of the hammers. The removable door 81 permits ready access to the interior of the crushing chamber 12, and the removable upper casing above the pulverizing chamber 11 and the fan chamber 14 permits ready access to these chambers. In neither instance is it necessary to disturb the feeder 58 or the chute 55.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A pulverizing apparatus comprising a hollow casing shaped to provide a crushing chamber and a pulverizing chamber laterally adjacent to one another, the pulverizing chamber having a centrally located outlet on the side opposite the crushing chamber, an upright wall entirely separating the chambers with the exception of a relatively small opening in the lower portion thereof, a rotatable crushing rotor in the crushing chamber, a rotatable pulverizing rotor in the pulverizing chamber, driv ing means for said rotors, means to supply coarse material to the upper portion of the crushing chamber above the crushing rotor, a grid located directly beneath the crushing rotor and providing openings for the escape of crushed material downwardly through the gird, and means providing an opening beneath the said upright wall for the escape of the crushed material from beneath the grid laterally into the pulverizing chamber.

2. A pulverizing apparatus as set forth in claim 1, in which the crushing rotor comprises a series of hammers arranged to strike the in-coming material and to whirl the same, the openings in the grid being inclined outwardly and forwardly at a considerable angle in the direction of rotation so that the crushed material may travel through these openings while continuing its whirling movement.

3. A pulverizing apparatus as set forth in claim 2, in which a plate structure is spaced beneath the grid and provides an inclined surface arranged to receive the whirling material issuing from the grid openings and to deflect the same laterally through the opening into the pulverizing chamber, the upper surface of the plate structure flaring radially outwardly in a direction toward the opening into the pulverizing chamber.

4. A pulverizing apparatus as set forth in claim 2, in which means is provided to supply a stream of hot air to the upper portion of the crushing chamber with the coarse material, and a fan is provided to withdraw air and pulverized material from the central outlet of the pulverizing chamber.

5. A pulverizing apparatus comprising a hollow casing, two spaced upright walls dividing the interior of the easing into a pulverizing chamber, a crushing chamber at one side of the pulverizing chamber, and a fan chamber at the other side of the pulverizing chamber, the wall between the pulverizing chamber and the fan chamber having a centrally located opening therein forming an outlet for the pulverizing chamber, a horizontal rotatable shaft extending through the chambers, a fan mounted on the shaft within the fan chamber, an upright disk mounted on the shaft within the pulverizing chamber, impact pegs mounted on the outlet side of the disk, stationary pegs mounted on the wall of the pulverizing chamber adjacent to the impact pegs, a crushing rotor mounted on the shaft within the crushing chamber and having peripherally located crushing hammers, means to deliver coarse material to the upper portion of the crushing chamber directly above the hammers, an arcuate grid beneath the hammers and substantially coaxial with the shaft, the grid having openings therethrough which are inclined outwardly and forwardly at a considerable angle in the direction of rotation, the wall between the crushing chamber and the pulverizing chamber having an opening therebeneath forming an inlet to the lower portion of the pulverizing chamber at the side of the upright disk away from the outlet of the chamber, said opening being shaped substantially as a circular ring sector coaxial with the grid, and a plate structure located beneath the grid and flaring radially outward in a direction toward the said inlet to the puverizing chamber to deflect the whirling crushed material through the said inlet.

References Cited in the file of this patent UNITED STATES PATENTS 769,253 Cox Sept. 6, 1904 1,427,842 Plaisted Sept. 5, 1922 1,714,132 Molz May 21, 1929 1,719,831 Daniels July 9, 1929 1,801,842 Briggs Apr. 21, 1931 2,031,683 Armstrong Feb. 25, 1936 2,172,096 Alfred Sept. 5, 1939 2,478,733 Wright Aug. 9, 1949 FOREIGN PATENTS 548,473 France Oct. 23, 1922 

